1. Field of the Invention
The present invention relates to a peer to peer (P2P) information sharing system including a plurality of node devices, which are connected each other via a network, particularly relates to a technical field for updating shared information memorized respectively in the node devices.
2. Discussion of Related Art
In such a peer to peer information delivery system, as disclosed in Non Patent Document 1, for example, an overlay network is logically configured by use of a distributed hash table (hereinafter referred to as DHT). Each of node devices which participate in the overlay network does not recognize link information (for example, IP address) of all the node devices, but retains only part of link information, which is obtained on participation or the like, and data inquiry or the like is carried out on the basis of such the link information.    Non Patent Document 1: Lightweight Load Balancing for Distributed Hash Tables, TECHNICAL REPORT OF IEICE by THE INSTITUTE OF ELECTRONICS, INFORMATION AND COMMUNICATION ENGINEERS